genetlink: use idr to track families
Since generic netlink family IDs are small integers, allocated
densely, IDR is an ideal match for lookups. Replace the existing
hand-written hash-table with IDR for allocation and lookup.
This lets the families only be written to once, during register,
since the list_head can be removed and removal of a family won't
cause any writes.
It also slightly reduces the code size (by about 1.3k on x86-64).
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index ca582ee..8565992 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -17,6 +17,7 @@
#include <linux/mutex.h>
#include <linux/bitmap.h>
#include <linux/rwsem.h>
+#include <linux/idr.h>
#include <net/sock.h>
#include <net/genetlink.h>
@@ -58,10 +59,8 @@ static void genl_unlock_all(void)
up_write(&cb_lock);
}
-#define GENL_FAM_TAB_SIZE 16
-#define GENL_FAM_TAB_MASK (GENL_FAM_TAB_SIZE - 1)
+static DEFINE_IDR(genl_fam_idr);
-static struct list_head family_ht[GENL_FAM_TAB_SIZE];
/*
* Bitmap of multicast groups that are currently in use.
*
@@ -86,45 +85,29 @@ static unsigned long mc_group_start = 0x3 | BIT(GENL_ID_CTRL) |
static unsigned long *mc_groups = &mc_group_start;
static unsigned long mc_groups_longs = 1;
-static int genl_ctrl_event(int event, struct genl_family *family,
+static int genl_ctrl_event(int event, const struct genl_family *family,
const struct genl_multicast_group *grp,
int grp_id);
-static inline unsigned int genl_family_hash(unsigned int id)
+static const struct genl_family *genl_family_find_byid(unsigned int id)
{
- return id & GENL_FAM_TAB_MASK;
+ return idr_find(&genl_fam_idr, id);
}
-static inline struct list_head *genl_family_chain(unsigned int id)
+static const struct genl_family *genl_family_find_byname(char *name)
{
- return &family_ht[genl_family_hash(id)];
-}
+ const struct genl_family *family;
+ unsigned int id;
-static struct genl_family *genl_family_find_byid(unsigned int id)
-{
- struct genl_family *f;
-
- list_for_each_entry(f, genl_family_chain(id), family_list)
- if (f->id == id)
- return f;
+ idr_for_each_entry(&genl_fam_idr, family, id)
+ if (strcmp(family->name, name) == 0)
+ return family;
return NULL;
}
-static struct genl_family *genl_family_find_byname(char *name)
-{
- struct genl_family *f;
- int i;
-
- for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
- list_for_each_entry(f, genl_family_chain(i), family_list)
- if (strcmp(f->name, name) == 0)
- return f;
-
- return NULL;
-}
-
-static const struct genl_ops *genl_get_cmd(u8 cmd, struct genl_family *family)
+static const struct genl_ops *genl_get_cmd(u8 cmd,
+ const struct genl_family *family)
{
int i;
@@ -135,26 +118,6 @@ static const struct genl_ops *genl_get_cmd(u8 cmd, struct genl_family *family)
return NULL;
}
-/* Of course we are going to have problems once we hit
- * 2^16 alive types, but that can only happen by year 2K
-*/
-static u16 genl_generate_id(void)
-{
- static u16 id_gen_idx = GENL_MIN_ID;
- int i;
-
- for (i = 0; i <= GENL_MAX_ID - GENL_MIN_ID; i++) {
- if (id_gen_idx != GENL_ID_VFS_DQUOT &&
- id_gen_idx != GENL_ID_PMCRAID &&
- !genl_family_find_byid(id_gen_idx))
- return id_gen_idx;
- if (++id_gen_idx > GENL_MAX_ID)
- id_gen_idx = GENL_MIN_ID;
- }
-
- return 0;
-}
-
static int genl_allocate_reserve_groups(int n_groups, int *first_id)
{
unsigned long *new_groups;
@@ -295,7 +258,7 @@ static int genl_validate_assign_mc_groups(struct genl_family *family)
return err;
}
-static void genl_unregister_mc_groups(struct genl_family *family)
+static void genl_unregister_mc_groups(const struct genl_family *family)
{
struct net *net;
int i;
@@ -358,6 +321,7 @@ static int genl_validate_ops(const struct genl_family *family)
int genl_register_family(struct genl_family *family)
{
int err, i;
+ int start = GENL_START_ALLOC, end = GENL_MAX_ID;
err = genl_validate_ops(family);
if (err)
@@ -370,34 +334,20 @@ int genl_register_family(struct genl_family *family)
goto errout_locked;
}
+ /*
+ * Sadly, a few cases need to be special-cased
+ * due to them having previously abused the API
+ * and having used their family ID also as their
+ * multicast group ID, so we use reserved IDs
+ * for both to be sure we can do that mapping.
+ */
if (family == &genl_ctrl) {
- family->id = GENL_ID_CTRL;
- } else {
- u16 newid;
-
- /* this should be left zero in the struct */
- WARN_ON(family->id);
-
- /*
- * Sadly, a few cases need to be special-cased
- * due to them having previously abused the API
- * and having used their family ID also as their
- * multicast group ID, so we use reserved IDs
- * for both to be sure we can do that mapping.
- */
- if (strcmp(family->name, "pmcraid") == 0)
- newid = GENL_ID_PMCRAID;
- else if (strcmp(family->name, "VFS_DQUOT") == 0)
- newid = GENL_ID_VFS_DQUOT;
- else
- newid = genl_generate_id();
-
- if (!newid) {
- err = -ENOMEM;
- goto errout_locked;
- }
-
- family->id = newid;
+ /* and this needs to be special for initial family lookups */
+ start = end = GENL_ID_CTRL;
+ } else if (strcmp(family->name, "pmcraid") == 0) {
+ start = end = GENL_ID_PMCRAID;
+ } else if (strcmp(family->name, "VFS_DQUOT") == 0) {
+ start = end = GENL_ID_VFS_DQUOT;
}
if (family->maxattr && !family->parallel_ops) {
@@ -410,11 +360,15 @@ int genl_register_family(struct genl_family *family)
} else
family->attrbuf = NULL;
- err = genl_validate_assign_mc_groups(family);
- if (err)
+ family->id = idr_alloc(&genl_fam_idr, family,
+ start, end + 1, GFP_KERNEL);
+ if (!family->id)
goto errout_locked;
- list_add_tail(&family->family_list, genl_family_chain(family->id));
+ err = genl_validate_assign_mc_groups(family);
+ if (err)
+ goto errout_remove;
+
genl_unlock_all();
/* send all events */
@@ -425,6 +379,8 @@ int genl_register_family(struct genl_family *family)
return 0;
+errout_remove:
+ idr_remove(&genl_fam_idr, family->id);
errout_locked:
genl_unlock_all();
return err;
@@ -439,32 +395,29 @@ EXPORT_SYMBOL(genl_register_family);
*
* Returns 0 on success or a negative error code.
*/
-int genl_unregister_family(struct genl_family *family)
+int genl_unregister_family(const struct genl_family *family)
{
- struct genl_family *rc;
-
genl_lock_all();
- list_for_each_entry(rc, genl_family_chain(family->id), family_list) {
- if (family->id != rc->id || strcmp(rc->name, family->name))
- continue;
-
- genl_unregister_mc_groups(family);
-
- list_del(&rc->family_list);
- up_write(&cb_lock);
- wait_event(genl_sk_destructing_waitq,
- atomic_read(&genl_sk_destructing_cnt) == 0);
- genl_unlock();
-
- kfree(family->attrbuf);
- genl_ctrl_event(CTRL_CMD_DELFAMILY, family, NULL, 0);
- return 0;
+ if (genl_family_find_byid(family->id)) {
+ genl_unlock_all();
+ return -ENOENT;
}
- genl_unlock_all();
+ genl_unregister_mc_groups(family);
- return -ENOENT;
+ idr_remove(&genl_fam_idr, family->id);
+
+ up_write(&cb_lock);
+ wait_event(genl_sk_destructing_waitq,
+ atomic_read(&genl_sk_destructing_cnt) == 0);
+ genl_unlock();
+
+ kfree(family->attrbuf);
+
+ genl_ctrl_event(CTRL_CMD_DELFAMILY, family, NULL, 0);
+
+ return 0;
}
EXPORT_SYMBOL(genl_unregister_family);
@@ -480,7 +433,7 @@ EXPORT_SYMBOL(genl_unregister_family);
* Returns pointer to user specific header
*/
void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
- struct genl_family *family, int flags, u8 cmd)
+ const struct genl_family *family, int flags, u8 cmd)
{
struct nlmsghdr *nlh;
struct genlmsghdr *hdr;
@@ -539,7 +492,7 @@ static int genl_lock_done(struct netlink_callback *cb)
return rc;
}
-static int genl_family_rcv_msg(struct genl_family *family,
+static int genl_family_rcv_msg(const struct genl_family *family,
struct sk_buff *skb,
struct nlmsghdr *nlh)
{
@@ -651,7 +604,7 @@ static int genl_family_rcv_msg(struct genl_family *family,
static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
{
- struct genl_family *family;
+ const struct genl_family *family;
int err;
family = genl_family_find_byid(nlh->nlmsg_type);
@@ -682,7 +635,7 @@ static void genl_rcv(struct sk_buff *skb)
static struct genl_family genl_ctrl;
-static int ctrl_fill_info(struct genl_family *family, u32 portid, u32 seq,
+static int ctrl_fill_info(const struct genl_family *family, u32 portid, u32 seq,
u32 flags, struct sk_buff *skb, u8 cmd)
{
void *hdr;
@@ -769,7 +722,7 @@ static int ctrl_fill_info(struct genl_family *family, u32 portid, u32 seq,
return -EMSGSIZE;
}
-static int ctrl_fill_mcgrp_info(struct genl_family *family,
+static int ctrl_fill_mcgrp_info(const struct genl_family *family,
const struct genl_multicast_group *grp,
int grp_id, u32 portid, u32 seq, u32 flags,
struct sk_buff *skb, u8 cmd)
@@ -812,37 +765,30 @@ static int ctrl_fill_mcgrp_info(struct genl_family *family,
static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
{
-
- int i, n = 0;
+ int n = 0;
struct genl_family *rt;
struct net *net = sock_net(skb->sk);
- int chains_to_skip = cb->args[0];
- int fams_to_skip = cb->args[1];
+ int fams_to_skip = cb->args[0];
+ unsigned int id;
- for (i = chains_to_skip; i < GENL_FAM_TAB_SIZE; i++) {
- n = 0;
- list_for_each_entry(rt, genl_family_chain(i), family_list) {
- if (!rt->netnsok && !net_eq(net, &init_net))
- continue;
- if (++n < fams_to_skip)
- continue;
- if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).portid,
- cb->nlh->nlmsg_seq, NLM_F_MULTI,
- skb, CTRL_CMD_NEWFAMILY) < 0)
- goto errout;
- }
+ idr_for_each_entry(&genl_fam_idr, rt, id) {
+ if (!rt->netnsok && !net_eq(net, &init_net))
+ continue;
- fams_to_skip = 0;
+ if (n++ < fams_to_skip)
+ continue;
+
+ if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).portid,
+ cb->nlh->nlmsg_seq, NLM_F_MULTI,
+ skb, CTRL_CMD_NEWFAMILY) < 0)
+ break;
}
-errout:
- cb->args[0] = i;
- cb->args[1] = n;
-
+ cb->args[0] = n;
return skb->len;
}
-static struct sk_buff *ctrl_build_family_msg(struct genl_family *family,
+static struct sk_buff *ctrl_build_family_msg(const struct genl_family *family,
u32 portid, int seq, u8 cmd)
{
struct sk_buff *skb;
@@ -862,7 +808,7 @@ static struct sk_buff *ctrl_build_family_msg(struct genl_family *family,
}
static struct sk_buff *
-ctrl_build_mcgrp_msg(struct genl_family *family,
+ctrl_build_mcgrp_msg(const struct genl_family *family,
const struct genl_multicast_group *grp,
int grp_id, u32 portid, int seq, u8 cmd)
{
@@ -892,7 +838,7 @@ static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = {
static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
{
struct sk_buff *msg;
- struct genl_family *res = NULL;
+ const struct genl_family *res = NULL;
int err = -EINVAL;
if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
@@ -936,7 +882,7 @@ static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
return genlmsg_reply(msg, info);
}
-static int genl_ctrl_event(int event, struct genl_family *family,
+static int genl_ctrl_event(int event, const struct genl_family *family,
const struct genl_multicast_group *grp,
int grp_id)
{
@@ -1005,25 +951,24 @@ static struct genl_family genl_ctrl = {
static int genl_bind(struct net *net, int group)
{
- int i, err = -ENOENT;
+ struct genl_family *f;
+ int err = -ENOENT;
+ unsigned int id;
down_read(&cb_lock);
- for (i = 0; i < GENL_FAM_TAB_SIZE; i++) {
- struct genl_family *f;
- list_for_each_entry(f, genl_family_chain(i), family_list) {
- if (group >= f->mcgrp_offset &&
- group < f->mcgrp_offset + f->n_mcgrps) {
- int fam_grp = group - f->mcgrp_offset;
+ idr_for_each_entry(&genl_fam_idr, f, id) {
+ if (group >= f->mcgrp_offset &&
+ group < f->mcgrp_offset + f->n_mcgrps) {
+ int fam_grp = group - f->mcgrp_offset;
- if (!f->netnsok && net != &init_net)
- err = -ENOENT;
- else if (f->mcast_bind)
- err = f->mcast_bind(net, fam_grp);
- else
- err = 0;
- break;
- }
+ if (!f->netnsok && net != &init_net)
+ err = -ENOENT;
+ else if (f->mcast_bind)
+ err = f->mcast_bind(net, fam_grp);
+ else
+ err = 0;
+ break;
}
}
up_read(&cb_lock);
@@ -1033,21 +978,19 @@ static int genl_bind(struct net *net, int group)
static void genl_unbind(struct net *net, int group)
{
- int i;
+ struct genl_family *f;
+ unsigned int id;
down_read(&cb_lock);
- for (i = 0; i < GENL_FAM_TAB_SIZE; i++) {
- struct genl_family *f;
- list_for_each_entry(f, genl_family_chain(i), family_list) {
- if (group >= f->mcgrp_offset &&
- group < f->mcgrp_offset + f->n_mcgrps) {
- int fam_grp = group - f->mcgrp_offset;
+ idr_for_each_entry(&genl_fam_idr, f, id) {
+ if (group >= f->mcgrp_offset &&
+ group < f->mcgrp_offset + f->n_mcgrps) {
+ int fam_grp = group - f->mcgrp_offset;
- if (f->mcast_unbind)
- f->mcast_unbind(net, fam_grp);
- break;
- }
+ if (f->mcast_unbind)
+ f->mcast_unbind(net, fam_grp);
+ break;
}
}
up_read(&cb_lock);
@@ -1087,10 +1030,7 @@ static struct pernet_operations genl_pernet_ops = {
static int __init genl_init(void)
{
- int i, err;
-
- for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
- INIT_LIST_HEAD(&family_ht[i]);
+ int err;
err = genl_register_family(&genl_ctrl);
if (err < 0)
@@ -1118,7 +1058,7 @@ subsys_initcall(genl_init);
* You cannot use this function with a family that has parallel_ops
* and you can only use it within (pre/post) doit/dumpit callbacks.
*/
-struct nlattr **genl_family_attrbuf(struct genl_family *family)
+struct nlattr **genl_family_attrbuf(const struct genl_family *family)
{
if (!WARN_ON(family->parallel_ops))
lockdep_assert_held(&genl_mutex);
@@ -1156,8 +1096,9 @@ static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group,
return err;
}
-int genlmsg_multicast_allns(struct genl_family *family, struct sk_buff *skb,
- u32 portid, unsigned int group, gfp_t flags)
+int genlmsg_multicast_allns(const struct genl_family *family,
+ struct sk_buff *skb, u32 portid,
+ unsigned int group, gfp_t flags)
{
if (WARN_ON_ONCE(group >= family->n_mcgrps))
return -EINVAL;
@@ -1166,7 +1107,7 @@ int genlmsg_multicast_allns(struct genl_family *family, struct sk_buff *skb,
}
EXPORT_SYMBOL(genlmsg_multicast_allns);
-void genl_notify(struct genl_family *family, struct sk_buff *skb,
+void genl_notify(const struct genl_family *family, struct sk_buff *skb,
struct genl_info *info, u32 group, gfp_t flags)
{
struct net *net = genl_info_net(info);
